From: Michael Strauss <michael.strauss@xxxxxxx>
[ Upstream commit bc2fde42e2418808dbfc04de1a6da91d7d31cf1a ]
[WHY]
i2c_read is called to differentiate passive DP->HDMI and DP->DVI-D dongles
The call is expected to fail in DVI-D case but pass in HDMI case
Some HDMI dongles have a chance to fail as well, causing misdetection as DVI-D
[HOW]
Retry i2c_read to ensure failed result is valid
Signed-off-by: Michael Strauss <michael.strauss@xxxxxxx>
Reviewed-by: Tony Cheng <Tony.Cheng@xxxxxxx>
Acked-by: Leo Li <sunpeng.li@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
.../gpu/drm/amd/display/dc/core/dc_link_ddc.c | 24 ++++++++++++++-----
1 file changed, 18 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link_ddc.c b/drivers/gpu/drm/amd/display/dc/core/dc_link_ddc.c
index e6da8506128bd..623c1ab4d3db2 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link_ddc.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_ddc.c
@@ -374,6 +374,7 @@ void dal_ddc_service_i2c_query_dp_dual_mode_adaptor(
enum display_dongle_type *dongle = &sink_cap->dongle_type;
uint8_t type2_dongle_buf[DP_ADAPTOR_TYPE2_SIZE];
bool is_type2_dongle = false;
+ int retry_count = 2;
struct dp_hdmi_dongle_signature_data *dongle_signature;
/* Assume we have no valid DP passive dongle connected */
@@ -386,13 +387,24 @@ void dal_ddc_service_i2c_query_dp_dual_mode_adaptor(
DP_HDMI_DONGLE_ADDRESS,
type2_dongle_buf,
sizeof(type2_dongle_buf))) {
- *dongle = DISPLAY_DONGLE_DP_DVI_DONGLE;
- sink_cap->max_hdmi_pixel_clock = DP_ADAPTOR_DVI_MAX_TMDS_CLK;
+ /* Passive HDMI dongles can sometimes fail here without retrying*/
+ while (retry_count > 0) {
+ if (i2c_read(ddc,
+ DP_HDMI_DONGLE_ADDRESS,
+ type2_dongle_buf,
+ sizeof(type2_dongle_buf)))
+ break;
+ retry_count--;
+ }
+ if (retry_count == 0) {
+ *dongle = DISPLAY_DONGLE_DP_DVI_DONGLE;
+ sink_cap->max_hdmi_pixel_clock = DP_ADAPTOR_DVI_MAX_TMDS_CLK;
- CONN_DATA_DETECT(ddc->link, type2_dongle_buf, sizeof(type2_dongle_buf),
- "DP-DVI passive dongle %dMhz: ",
- DP_ADAPTOR_DVI_MAX_TMDS_CLK / 1000);
- return;
+ CONN_DATA_DETECT(ddc->link, type2_dongle_buf, sizeof(type2_dongle_buf),
+ "DP-DVI passive dongle %dMhz: ",
+ DP_ADAPTOR_DVI_MAX_TMDS_CLK / 1000);
+ return;
+ }
}
/* Check if Type 2 dongle.*/
--
2.20.1
